Are You at Risk of Brain Metastasis?

Brain metastasis is a term used to describe a brain tumour or cancer which originates from a tumour in another part of the body that has spread to the brain. This type of tumour is the most common brain tumour in adults, with an incidence of 7-14 persons per 100,000 population.

Anywhere from 10 to 26% of patients who die from their cancer will have developed brain metastases. Not infrequently, a tumour in the brain may be the first manifestation of a ‘silent’ cancer occurring in another part of the body (as high as 20%).

In recent times, more and more people are being diagnosed with this condition. A number of reasons can account for this. Firstly, increased usage and advances in magnetic resonance imaging (MRI) of the brain now allow for the early detection of small asymptomatic tumours. In addition, widespread use of systemic therapies has improved survival from primary cancers who later develop metastasis.

HOW DO TUMOUR CELLS SPREAD TO THE BRAIN?

Tumour cells can break away from the primary tumour and reach the brain via the bloodstream. In the brain, these tumour cells multiply and invade normal brain tissue, resulting in displacement, inflammation, and swelling.

Some metastatic brain tumours appear many years after the primary cancer. Others metastasize so quickly that they are identified even before the primary cancer.

When cancer cells reach the brain and form a mass, it may lead to a variety of symptoms depending the part of brain which is affected. Often there is more than one metastatic tumour in the brain of patient with cancer.

WHAT ARE THE COMMON SYMPTOMS OF BRAIN METASTASES?

• Headaches
• Seizures
• Weakness in the arms or legs
• Loss of balance
• Memory loss
• Speech disturbance
• Behavioural or personality changes
• Blurred vision/double vision
• Numbness
• Hearing loss

WHO IS AT RISK OF DEVELOPING METASTATIC BRAIN CANCER?

About one-third of patients with cancer will develop one or more metastatic brain tumours. The risk for metastatic brain tumours begins to increase after age 45, and is highest in those over 65.

WHICH TUMOURS COMMONLY METASTASIZE?

Any cancer can spread to the brain, but the types most likely to cause brain metastases originate from the lung, breast, colon, kidney, and a skin cancer knows as melanoma.

HOW DO YOU EVALUATE PATIENTS SUSPECTED TO HAVE METASTATIC BRAIN TUMOURS?

A doctor will usually take a detailed history and perform a physical examination focusing on symptoms, duration, and intensity. Focused questions about headaches, blurry vision, and nausea are asked. A complete neurologic examination should be performed. This examination should include an assessment of strength, sensation, coordination, reflexes, cerebellar function, proprioception, cranial nerve function, speech, thought, vision, and memory. An ophthalmic examination should be performed to evaluate for papilledema. Additional information including age, performance status, and status of systemic cancer burden should be gathered to understand the disease course and guide future therapeutic intervention.

Often a CT scan of the brain is ordered as it is the most rapid investigation in emergency situations. An MRI brain with Contrast however is the Gold standard for diagnosis and all patients should undergo one. MR allows for a determination of the number and anatomical location of tumours and the degree of associated edema. Basic laboratory assessment including complete blood count, metabolic panel, and liver function test should also be performed.

HOW CAN THESE TUMOURS BE TREATED?

Upon detection, steroids are commonly prescribed as a temporary measure to reduce the swelling related to the tumour. Definitive treatment includes surgical removal of the tumour, stereotactic radiosurgery (SRS) or whole brain radiation therapy (WBRT). Surgery is usually utilized to treat fit patient with large tumours (>3cm) with significant compression of brain and impending brain herniation.

Techniques like minimally invasive approaches as well as awake brain surgery make removal of tumours near vital brain areas very safe and effective in this era. Smaller tumours as well as multiple tumours are best treated with Stereotactic Radiosurgery techniques such the Gamma Knife. WBRT while commonly used for multiple metastasis in the past is less and less popular due to the cognitive side effects seen in patients after treatment with no added benefit to survival. The above treatment options can be used in combination in order to get the best response.

Dr. Regunath Kandasamy

Consultant Neurosurgeon, 

Gleneagles Hospital Kuala Lumpur 

This article was first published on The Expat Magazine, July 2024 edition.